What does the part of the problem, " be relations
from {1, 2, 3} to {1, 2, 3, 4}" mean?

A "relation from set A to set B" is a set of ordered pairs in which the first member of each pair is in A and the second member is in B.
So, here, "relations from {1, 2, 3} to {1, 2, 3, 4}" are sets of ordered pair where the first member of each pair one of 1, 2, or 3 and the second member is one of 1, 2, 3, or 4. You should see that this is true for the given relations.